Chemoprevention can be a major component of the control of pancreatic cancer, one of the deadliest malignancies. Preclinical data indicate that NSAIDs prevent pancreatic cancer, but epidemiological studies are conflicting, perhaps reflecting lack of sufficient efficacy by traditional NSAIDs. Of note, NSAID side effects preclude their large-scale application in cancer prevention. The novel nitric oxide-releasing aspirin (NO-ASA) consists of an ASA molecule and a NO-releasing moiety linked via a chemical spacer. There are three positional isomers of NO-ASA (ortho, meta and para). Two studies have documented its superior safety in humans. We have observed that NO-aspirin (NO-ASA) is 695-fold more potent than ASA in inhibiting the growth of cultured pancreatic cancer cells. Our preliminary study also shows that NO-ASA inhibits pancreatic cancer formation by 89.9% in hamsters treated with the carcinogen BOP. These findings combined with its superior efficacy and safety, make NO-ASA a promising chemopreventive agent and constitute a compelling argument to study its mechanism of action in pancreatic carcinogenesis. We propose to evaluate two hypotheses: a) that NO-ASA is a chemopreventive agent against pancreatic cancer, and b) that NO-ASA inhibits the NF-kappaB pathway in the pancreas and that this effect accounts, to a significant degree, for its ability to prevent pancreatic cancer. NF-kappaB activation is a key event in pancreatic carcinogenesis and our preliminary data indicate that NO-ASA strongly inhibits it. We will study the three positional isomers of NO-ASA. Our specific aims are: 1) Determine in cultured pancreatic cancer cells the effect of NO-ASA on the NF-kappaB pathway. Specifically, we will study the inhibition of NF-kappaB activation by NO-ASA and determine its mechanism; the effect of NO-ASA on pancreatic cancer cell kinetics and determine whether NF-kappaB inhibition is required for this effect; assess the expression of NF-kappaB dependent genes that mediate it; and determine which part of the NO-ASA molecule is critical for its effect on NF-kappaB. Based on the results of this Specific Aim, we will select the most promising NO-ASA positional isomer to: 2) Determine in an animal model of pancreatic cancer the efficacy of NO-ASA against pancreatic carcinogenesis and elucidate its in vivo effect on NF-kappaB. Specifically, we will determine in the pancreas tumor incidence and multiplicity; inhibition of NF-kappaB activation; effects on cell proliferation, apoptosis and relevant NF-kappaB dependent genes that mediate this effect. These studies will provide mechanistic data and a detailed preclinical evaluation, setting the stage for the clinical assessment of NO-ASA against pancreatic cancer.